title: Hierarchical and helical self-assembly of ADP-ribosyl cyclase into large-scale protein microtubes.
abstract: Proteins are macromolecules with characteristic structures and biological functions. It is extremely challenging to obtain protein microtube structures through self-assembly as proteins are very complex and flexible. Here we present a strategy showing how a specific protein, ADP-ribosyl cyclase, helically self-assembles from monomers into hexagonal nanochains and further to highly ordered crystalline microtubes. The structures of protein nanochains and consequently self-assembled superlattice were determined by X-ray crystallography at 4.5 A resolution and imaged by scanning electron microscopy. The protein initially forms into dimers that have a fixed size of 5.6 nm, and then, helically self-assembles into 35.6 nm long hexagonal nanochains. One such nanochain consists of six dimers (12 monomers) that stack in order by a pseudo P6(1) screw axis. Seven nanochains produce a series of large-scale assemblies, nanorods, forming the building blocks for microrods. A proposed aging process of microrods results in the formation of hollow microstructures. Synthesis and characterization of large scale self-assembled protein microtubes may pave a new pathway, capable of not only understanding the self-assembly dynamics of biological materials, but also directing design and fabrication of multifunctional nanobuilding blocks with particular applications in biomedical engineering.
authors.forename: Qun
authors.initials: Q
authors.lastname: Liu
authors.forename: Irina A
authors.initials: IA
authors.lastname: Kriksunov
authors.forename: Zhongwu
authors.initials: Z
authors.lastname: Wang
authors.forename: Richard
authors.initials: R
authors.lastname: Graeff
authors.forename: Hon Cheung
authors.initials: HC
authors.lastname: Lee
authors.forename: Quan
authors.initials: Q
authors.lastname: Hao
mesh_terms: D036541:ADP-ribosyl Cyclase / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008855:Microscopy, Electron, Scanning; D011487:Protein Conformation
chemical_list: D036541:ADP-ribosyl Cyclase